Ti/4H-SiC schottky barrier modulation by ultrathin a-SiC:H interface layer

The possibility of Schottky barrier height (SBH) modulation of conventional Ti/4H-SiC Schottky diodes by inserting an ultrathin a-SiC:H layer and the influence of annealing at 600 °C are investigated. Amorphous SiC:H layers between 0.7 and 4 nm thickness were grown on the 4H-SiC surface using plasma-enhanced chemical vapor deposition prior to Ti deposition. Diode properties are extracted using current-voltage and capacitance-voltage measurements between 300 and 450 K and compared to conventional Ti/4H-SiC diodes. Transmission electron microscopy and X-ray diffraction were applied to investigate the microstructure of as-deposited and annealed diodes. The integration of an a-SiC:H interface layer in combination with thermal annealing resulted in very ideal diode characteristics, whereas the duration of the annealing can be used to adjust the SBH. A room temperature SBH range between 0.78 and 1.16 V could be covered using different interface layer thicknesses and annealing durations.